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Method for preparing hydrophobic silica aerogel with low cost

A silicon dioxide and hydrophobic technology, applied in chemical instruments and methods, inorganic chemistry, silicon compounds, etc., can solve the problems of increased production costs, large energy consumption, cumbersome processes, etc., achieve low cost, improve thermal insulation performance, The effect of simple preparation process

Active Publication Date: 2012-11-07
蓝烟(北京)科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since supercritical drying requires a high temperature and high pressure process, the energy consumption is large, the process is cumbersome, it is dangerous, and the yield is low, which is not conducive to industrial production. The high cost seriously restricts the SiO 2 Popular application of airgel
In order to overcome this problem, many researchers have tried to replace supercritical drying with normal pressure drying, freeze drying and other methods to prepare SiO2. 2 Airgel, but the prepared products have deficiencies in thermal insulation performance and other aspects
[0004] In addition, the preparation of SiO 2 Commonly used raw materials for airgel mainly include water glass, orthosilicate, silica sol, etc. In order to improve the product’s hydrophobicity, flexibility, and mechanical strength, additional surface modification steps are usually used, which further improves production. cost

Method used

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  • Method for preparing hydrophobic silica aerogel with low cost
  • Method for preparing hydrophobic silica aerogel with low cost
  • Method for preparing hydrophobic silica aerogel with low cost

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Mix 50 milliliters of distilled water, 6.0 grams of dodecyltrimethylammonium chloride, and 260 milliliters of methyltrimethoxysilane. After stirring and mixing for 20 minutes, adjust the pH value to 4 with acetic acid, add 10 milliliters of methanol and stir for 10 minutes After that, it was left still at 25° C. for 60 minutes.

[0023] Mix 200 ml of urea solution with a mass concentration of 0.2 g / ml and temperature down to about 0°C into the above solution, stir and mix thoroughly, and then stand at 25°C for 12 hours to form a sol.

[0024] A gel was formed after aging the above sol at 70°C for 36 hours. Then, the formed gel was solvent exchanged and washed with methanol at 55° C. for 4 times, each time for 12 hours.

[0025] Subsequently, the gel was dried in a normal pressure environment at 50° C. for 24 hours to obtain a silica airgel product.

[0026] After testing, the thermal conductivity of the above silica airgel product at 25°C is 0.015W / k·m.

[0027] fig...

Embodiment 2

[0029] Mix 290 ml of distilled water, 6.0 g of dodecyltrimethylammonium chloride, and 260 ml of methyltrimethoxysilane. After fully stirring and mixing for 20 minutes, adjust the pH value to 4 with acetic acid, add 10 ml of methanol and stir for 10 minutes After that, it was left still at 25° C. for 60 minutes.

[0030] Mix 240 ml of urea solution with a mass concentration of 0.2 g / ml and temperature down to about 0°C into the above solution, stir and mix thoroughly, and then stand at 25°C for 12 hours to form a sol.

[0031] A gel was formed after aging the above sol at 70°C for 36 hours. Then, the formed gel was solvent exchanged and washed with methanol at 55° C. for 4 times, each time for 12 hours.

[0032] Subsequently, the gel was dried in a normal pressure environment at 50° C. for 24 hours to obtain a silica airgel with strong hydrophobicity and excellent thermal insulation effect. The thermal conductivity at 25°C can reach 0.022W / k·m.

Embodiment 3

[0034] Mix 290 ml of distilled water, 6.0 g of dodecyltrimethylammonium chloride, and 260 ml of methyltrimethoxysilane, stir and mix thoroughly for 20 minutes, adjust the pH value to 6 with acetic acid, add 10 ml of methanol and stir for 10 minutes After that, it was left still at 25° C. for 60 minutes.

[0035] Mix 240 ml of urea solution with a mass concentration of 0.2 g / ml and temperature down to about 0°C into the above solution, stir and mix thoroughly, and then stand at 25°C for 12 hours to form a sol.

[0036] A gel was formed after aging the above sol at 70°C for 36 hours. Then, the formed gel was solvent exchanged and washed with methanol at 55° C. for 4 times, each time for 12 hours.

[0037] Subsequently, the gel was dried in a normal pressure environment at 50° C. for 24 hours to obtain a silica airgel with strong hydrophobicity and excellent thermal insulation effect. The thermal conductivity at 25°C can reach 0.029W / k·m.

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Abstract

The invention relates to a method for preparing hydrophobic silica aerogel with low cost. By means of the method, siloxane with alkyl serves as the raw material, wet gel is prepared through a sol-gel method, and then the silica aerogel is prepared through a normal-pressure drying method. By controlling content of water in the solution and pH value of the solution and adding urea solution with the temperature of 0 DEG C, hydrophobic silica aerogel products with prominent thermal insulation performance can be produced. The method for producing hydrophobic silica aerogel requires no additional surface modification processes, is simple in process and low in cost and can perform industrial production conveniently.

Description

technical field [0001] The invention relates to the preparation and application of silica airgel. Background technique [0002] SiO 2 Airgel is a porous material with high specific surface area and low density. Due to the existence of nano-network structure, the material itself has special properties. It has a wide range of applications in many fields such as optics, electricity, acoustics, environmental protection, and metallurgy. The prospect is listed as the world's top ten popular science and technology by the 250th issue of "Science" in the United States. SiO 2 Because of its high-permeability three-dimensional porous nano-network structure, aerogel has very low solid heat conduction, and has a nano-hole structure that can prevent air convection heat conduction, and uses doping to reflect and absorb infrared radiation, so that SiO 2 Airgel material has become a light and high-efficiency thermal insulation material with extremely low thermal conductivity; it is also ...

Claims

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Application Information

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IPC IPC(8): C01B33/158
Inventor 林二军
Owner 蓝烟(北京)科技有限公司
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